JP6094948B2 - Manufacturing method of breathable member for mold - Google Patents

Description

  The present invention relates to a mold member that can be used for a mold, a mold breathable member using the mold member, a mold member, and a method for manufacturing the mold breathable member.

  Conventionally, a breathable durable mold used in a vacuum forming method is described in, for example, Japanese Patent Laid-Open No. 7-108348 (and corresponding CN 1041178C and US 5405570A) (Patent Document 1). Moreover, the manufacturing method of the air permeable molded object used for a vacuum forming method is described in Unexamined-Japanese-Patent No. 7-113103 (and corresponding CN1102607A and US5435967A) (patent document 2), for example.

JP-A-7-108348 JP 7-113103 A

The conventional breathable durable type described in Patent Document 1 has a problem that the strength is weak, and further, vacuum molding by pouring is possible, but since machining, electric discharge machining, and etching cannot be performed, injection molding is possible. Could not be used. The molded body described in Patent Document 2 has a problem that the strength is further weak.
Therefore, a mold material that has air permeability and high strength and can be used for injection molding has been desired. Furthermore, in order to improve the usability as a mold material, it has been desired to have workability.

The present invention has been made to satisfy conventional demands, and an object of the present invention is to provide a mold material having strength and workability in addition to air permeability.
Another object of the present invention is to provide a mold breathable member using the mold mold material, and a method for producing the mold mold member and the mold breathable member.

In order to achieve the above object, the mold material of the present invention forms a mixed material containing stainless steel fibers having a diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm, and stainless steel powder. The green body of this mixed material is heated and sintered, and the obtained sintered body is manufactured by nitriding by heating in a nitrogen atmosphere, and the average pore diameter of the air holes is 3 to 50 μm. According to the configured mold material, excellent air permeability is realized while maintaining strength, and it can be used for injection molding.

In the mold material of the present invention, preferably, the stainless steel fiber and the stainless steel powder are ferritic stainless steel.
According to the present invention configured as described above, it is more advantageous in terms of easy processing and corrosion resistance than austenitic stainless steel and martensitic stainless steel.

In the mold material of the present invention, the nitrogen content by nitriding is preferably 0.3 to 1.2% by weight with respect to 100% by weight of the stainless steel component.
According to the present invention configured as described above, it has an appropriate hardness required as a mold material and has excellent workability.

In the mold material according to the present invention, preferably, the mixed material further includes a copper powder or a copper tin alloy powder.
According to the present invention configured as described above, the toughness is improved and an excellent mold material is obtained.

  In the mold material according to the present invention, preferably, the mixed material includes 20 to 80% by weight of stainless steel fibers and 20 to 80% by weight of stainless steel powder as a stainless steel component. 1-10 weight% copper powder or copper tin alloy powder is included with respect to weight%.

  In the mold material according to the present invention, preferably, the porosity of the air holes is 15 to 35%.

  In the mold material according to the present invention, preferably, nitriding is performed while being held at 900 to 1050 ° C. in nitrogen gas or ammonia decomposition gas.

The air-permeable member for a mold of the present invention is obtained by subjecting the above-described mold material to electric discharge machining, etching, or machining, and is incorporated into the mold.
According to the mold breathable member of the present invention configured as described above, the gas ventability and resin fluidity can be improved by using the mold breathable member for the mold. The structure can be simplified, products that were difficult to injection mold can be molded, the molding cycle can be shortened, and gas defects can be prevented. That is, a net-like or lattice-like molded product can be reliably molded, and a thin object can be molded well. Furthermore, since the adhesiveness of the resin to the mold is high, it is possible to form the surface pattern faithfully and to eliminate the gloss unevenness, thus enabling no painting.

  A gas-permeable member for a mold according to the present invention is a gas-permeable member for a mold obtained by applying a pattern to the above-described mold material by electric discharge machining, etching, or machining. A mold in which an air permeable member is incorporated can be used for resin injection molding.

The mold breathable member of the present invention is a mold breathable member obtained by subjecting the above-described mold mold material to electrical discharge machining, etching, or machining, and this mold breathable member. A conduction hole for water flow is provided inside the member.
According to the present invention configured as described above, since the water conduction hole is provided inside the mold breathable member, the mold temperature can be kept constant, thereby stabilizing the mold. Quality and molding cycle can be obtained.

In the mold breathable member of the present invention, preferably, the inner surface of the conduction hole of the mold breathable member is sealed with a curing agent-blended epoxy resin.
According to the present invention configured as described above, the inner surface of the conduction hole of the mold breathable member is sealed with an epoxy resin containing a curing agent, so that water leakage from the conduction hole is surely prevented. can do.

The mold breathable member of the present invention is preferably a mold breathable member obtained by subjecting the above-described mold mold material to electric discharge machining, etching process, or machining, and after the machining, The processing oil or the etching liquid that has soaked into the air holes serving as the air holes is cleaned by air blowing.
According to the present invention configured as described above, in the air-permeable member for molds, the processing oil and the etching liquid immersed in the air holes are washed by air blowing by electric discharge machining, etching, or machining. Therefore, it is not necessary to perform complicated work or prepare a special device as in the prior art, and it is possible to clean the processing oil and the like safely and reliably.

In the mold breathable member of the present invention, the air permeability of the washed mold breathable member is preferably 50 cm ³ / cm ² · sec or more.

  The mold breathable member of the present invention is a mold breathable member obtained by machining the mold mold material described above, and the processed portion has a surface roughness of 3 μm to 20 μm.

  In the mold breathable member of the present invention, preferably, the processed portion has a surface roughness of 3.2 μm to 13.5 μm.

  In the mold breathable member of the present invention, the machining is preferably performed by a ball end mill, the rotation speed of the ball end mill is 3000 to 30000 rpm, and the feed speed of the ball end mill is 1000 to 2000 mm / min.

  The method for producing a mold member according to the present invention comprises forming a mixed material containing stainless steel fibers having a diameter in terms of diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and stainless steel powder. The green body is heated and sintered, and the obtained sintered body is heated and nitrided in a nitrogen atmosphere to produce a mold member having an average pore diameter of 3 to 50 μm.

  The method for producing a breathable member for a mold according to the present invention comprises forming a mixed material containing stainless steel fibers having a diameter converted diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and stainless steel powder, and mixing the mixture. The green body of the material is heated and sintered, and the obtained sintered body is heated and nitrided in a nitrogen atmosphere to produce a mold material having an average pore diameter of 3 to 50 μm. A mold breathable member is manufactured by electric discharge machining, etching process, or machining of a mold mold material, and a water conduction hole is provided inside the mold breathable member. A sealing treatment is performed on the inner surface of the resin with a curing agent-containing epoxy resin.

  The method for producing a breathable member for a mold according to the present invention comprises forming a mixed material containing stainless steel fibers having a diameter converted diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and stainless steel powder, and mixing the mixture. The green body of the material is heated and sintered, and the obtained sintered body is heated and nitrided in a nitrogen atmosphere to produce a mold material having an average pore diameter of 3 to 50 μm. A mold breathable member is manufactured by subjecting the mold material to electrical discharge machining, etching, or machining, and the processing oil or etchant that has soaked into the air holes after the machining is washed by air blow.

  The method for producing a breathable member for a mold according to the present invention comprises forming a mixed material containing stainless steel fibers having a diameter converted diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and stainless steel powder, and mixing the mixture. The green body of the material is heated and sintered, and the obtained sintered body is heated and nitrided in a nitrogen atmosphere to produce a mold material having an average pore diameter of 3 to 50 μm. A mold breathable member is manufactured by machining the mold material so that the processed portion has a surface roughness of 3 μm to 20 μm.

  In the method for producing a mold breathable member of the present invention, machining is performed by a ball end mill, the rotation speed of the ball end mill is 3000 to 30000 rpm, and the feed speed of the ball end mill is 1000 to 2000 mm / min.

It is a diagram which shows the sintering conditions of the green body of the mixed material at the time of manufacturing the metal mold | die material by embodiment of this invention. It is a diagram which shows the vacuum hardening conditions of the metal mold | die material at the time of manufacturing the metal mold | die material by embodiment of this invention. It is a partial top view which shows the ventilation member for metal mold | dies by other embodiment of this invention. It is sectional drawing seen along the IV-IV line of FIG. It is a fragmentary top sectional view which shows the other example of the ventilation member for metal mold | dies by other embodiment of this invention. It is a fragmentary top sectional view which shows the further another example of the ventilation member for metal mold | dies by other embodiment of this invention. It is a front view of the air permeable member for molds for explaining air blow washing of the air permeable member for metal molds by the embodiment of the present invention. It is a diagram which shows the relationship between the air permeability in the air blow cleaning of the air permeable member for metal mold | die by embodiment of this invention, and air blow time.

Hereinafter, with reference to the accompanying drawings, a mold material, a mold breathable member, a mold mold material, and a mold breathable member according to an embodiment of the present invention will be described.
First, with reference to FIG.1 and FIG.2, the metal mold | die material by embodiment of this invention and the manufacturing method of this metal mold | die material are demonstrated.

  The mold material according to the embodiment of the present invention is a mixed material including a ferritic stainless steel fiber having a diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and a ferritic stainless steel powder. A green body is obtained by press molding to obtain a green body, the obtained green body is heated and sintered, and the obtained sintered body is heated and nitrided in a nitrogen atmosphere. Furthermore, in this mold material, the average pore diameter is 3 to 50 μm.

  Here, the mold material according to the embodiment of the present invention is not limited to ferritic stainless steel, and may be, for example, austenitic stainless steel or martensitic stainless steel. However, austenitic stainless steels may be difficult to process, and martensitic stainless steels may have a problem of rusting due to deterioration of corrosion resistance depending on the components. Therefore, ferritic stainless steel is more advantageous in terms of easy processing and corrosion resistance than austenitic stainless steel and martensitic stainless steel.

  Moreover, the mixed material containing the ferritic stainless steel fiber and the ferritic stainless steel powder may further contain a copper powder or a copper tin alloy powder, in which case the toughness is improved by the characteristics of the copper alloy, It is an excellent mold material.

  The mixed material contains 20 to 80% by weight of stainless steel fiber and 20 to 80% by weight of stainless steel powder as a stainless steel component, and further 1 to 10% by weight with respect to 100% by weight of this stainless steel component. It is desirable to contain copper powder or copper tin alloy powder.

  Typical examples of ferritic stainless steel used as stainless steel fiber and stainless steel powder are SUS434 (C ≦ 0.1%, 16% ≦ Cr ≦ 19%, 0.5% ≦ Mo ≦ 2%) and SUS430 (C ≦ 0.03%, 16% ≦ Cr ≦ 19%).

For example, the stainless steel fiber is prepared by cutting a coil material having a thickness of 30 to 300 μm made of the above-described chemical components by an end face cutting method to prepare a long fiber having a diameter converted diameter of 30 to 300 μm, and cutting the long fiber with a cutter mill or the like. By doing this, a short fiber having a length of 0.4 to 5.0 mm is obtained, and this short fiber is used.
Here, a stainless steel fiber having a diameter converted diameter of 30 to 300 μm means a stainless steel fiber having a diameter of a perfect circle having a cross-sectional area equal to the cross-sectional area of the stainless steel fiber in a range of 30 to 300 μm.

A mixed material obtained by adding the above-described stainless steel fiber, stainless steel powder, and copper (Cu) powder or copper-tin alloy (Cu-Sn) powder is uniformly filled into a rubber mold for CIP method. A green body of a mixed material is obtained by pressure molding with a pressure of 4 ton / cm ² .

  The green body is heated and sintered in a vacuum atmosphere, and the obtained sintered body is continuously or reheated and held in nitrogen gas or ammonia decomposition gas at 900 ° C. to 1050 ° C. Thus, nitriding is performed by containing 0.3 to 1.2% by weight of nitrogen with respect to 100% by weight of the stainless steel component (stainless steel fiber and stainless steel powder) as the base metal.

  By the above molding, sintering and nitriding, it has fine pores (porosity 15 to 35%, average pore diameter 3 to 50 μm) on the entire surface, and it is necessary as a mold material without impairing machinability and corrosion resistance. A mold material having high strength and hardness (HMV 250 to 500) can be obtained. Further, in this mold material, the hardness can be controlled by performing a heat treatment.

  In the embodiment described above, the mold material is obtained by molding, sintering, and nitriding, but the present invention is not limited to this. That is, cooling and reheating treatment may be performed after nitriding. The reheating process is performed by, for example, a vacuum quenching process. Further, the cooling is performed, for example, at an average cooling rate of 5.5 ° C./min or higher and rapidly cooled to 250 ° C. or lower, and the reheating treatment is performed, for example, in a range of 600 to 680 ° C. was gotten.

  Next, Examples 1 to 6 of the mold material according to the embodiment of the present invention and Comparative Examples 1 to 4 for comparison with these Examples will be described.

  First, conditions of these examples and comparative examples will be described. As a stainless steel fiber, a stainless steel 100 μm coil material of SUS434 (C: 0.1%, Cr: 18%, Mo: 1%) is cut by an end face cutting method to obtain a long fiber having a diameter converted diameter of 60 to 150 μm. It was produced and cut with a cutter mill to obtain 0.4 to 5.0 mm short fibers, which were used.

  As the stainless steel powder, stainless steel powder of SUS434 (C: 0.05%, Cr: 17%, Mo: 2%) was used. The condition of the stainless steel powder is such that 90% or more is 150 μm or less.

  As the copper powder, electrolytic copper powder was used. The condition of the copper powder is such that a powder of 45 μm or less is 80% or more.

As a mixed material, 40% by weight of stainless steel fiber and 60% by weight of stainless steel powder were mixed, and further, 3% by weight of copper powder was added to 100% by weight of this stainless steel component to obtain a mixed material. The mixed material was uniformly filled into a rubber mold for CIP method and pressure-molded with a pressure of 3 ton / cm ² to obtain a green body (green compact). Next, the green body was sintered under the sintering conditions shown in FIG. 1 to obtain a sintered body.

FIG. 1 is a diagram showing sintering conditions for a green body of a mixed material when a mold material according to an embodiment of the present invention is manufactured. The horizontal axis in FIG. 1 indicates time (Hr), the vertical axis indicates temperature (° C.), the range indicated by P1 indicates a range of a vacuum degree of 1 × 10 ⁻² torr or less, and is indicated by P2. The range indicates the range of 10 torr of partial nitrogen, and the time point P3 indicates the time point of flowing nitrogen gas 3 kg / cm ² .

The sintering conditions shown in FIG. 1 will be described in detail. A block-like material of 250 mm × 200 mm × 100 mm (about 30 kg) is used as a test material. First, the test material is depressurized to 1 × 10 ⁻² torr or less in a vacuum sintering furnace, and then heated up to reach 550 ° C., and then the vaporized components are sufficiently degassed at 550 ° C. Therefore, the temperature was maintained for 30 minutes to obtain a vacuum of 1 × 10 ⁻² torr or less. Thereafter, the temperature was raised again to 1150 ° C., held at 1150 ° C. for 2 hours, and then cooled to 700 ° C.

  Here, when the temperature is raised again to 1150 ° C., partial nitrogen is allowed to flow at 10 torr (10/780 atm). The purpose of flowing partial nitrogen is to prevent Cr evaporation in the stainless steel when kept at a high vacuum temperature.

When the furnace is cooled to 700 ° C., nitrogen gas is flowed at 3 kg / cm ² to rapidly cool the specimen. The reason why the rapid cooling is started at 700 ° C. is to prevent the micro (microscopic) structure from changing after the transformation point.

  Next, the specimen was subjected to nitriding treatment under the conditions shown in Table 1. Table 1 also shows analysis values and hardness measurement values of the components of the obtained mold material.

In the nitriding treatment, the pressure is reduced to 1 × 10 ⁻² torr or less in a vacuum heat treatment furnace, and then the temperature is raised until the temperature reaches 700 ° C., and then 30 ° C. for sufficient degassing of vaporized components at 700 ° C. The temperature was kept for 1 minute to obtain a vacuum of 1 × 10 ⁻² torr or less. Thereafter, the temperature was raised again, and each holding temperature or holding time was changed, and nitriding was performed in a nitrogen atmosphere at 1 atm. A retention time of 30 minutes or more was required to obtain a uniform nitrogen content.

  As shown in Table 1, the non-nitriding material (Comparative Example 1) and the nitrogen content smaller than 0.3% (Comparative Example 2) have the hardness required as a mold material. Since it is below HMV250, it is inappropriate. Also, those having a nitrogen content greater than 1.2% (Comparative Example 3 and Comparative Example 4) produce a large amount of chromium nitride and have a hardness of HV500 or more, which is difficult to process and suitable as a mold material. hard. Here, “HMV” indicates micro Vickers hardness, which is a unit representing hardness, and is a value measured by a micro Vickers hardness meter (model number HMV-2000) manufactured by Shimadzu Corporation.

  Next, strength and holes will be described. Example 1 was selected from the examples shown in Table 1, and Table 2 shows the results of mechanical properties, pore diameter, and porosity of Example 1. Here, Example 1 is excellent in machinability and has a cutting speed equivalent to that of a conventional ordinary mold material (SKD61).

The mold material of Example 1 was processed and used as a mold. Rice universal ABS resin minimum thickness 0.7 mm, what band-type product dimensions 10 mm × 150 mm in 10 locations, was subjected to molding test, it can cleanly molded by injection pressure 98 kg / cm ^2, no gas burning Things were obtained. When a normal mold was used, the injection pressure was 138 kg / cm ² .

  Next, the vacuum quenching test will be described. Example 2 and Example 5 were selected from the examples in Table 1, and Table 3 shows the results of the vacuum quenching test.

Here, the vacuum quenching conditions will be described with reference to FIG. FIG. 2 is a diagram showing the vacuum quenching conditions of the mold material when manufacturing the mold material according to the embodiment of the present invention. In FIG. 2, the horizontal axis indicates time (Hr), the vertical axis indicates temperature (° C.), the range indicated by P11 and P13 indicates a range of a vacuum degree of about 1 × 10 ⁻² torr, and P12 indicates nitrogen. The time point at which 3 kg / cm ² of gas is supplied is shown, and P14 indicates that furnace cooling is being performed.

As shown in FIG. 2, first, the pressure is reduced to about 1 × 10 ⁻² torr in a vacuum heat treatment furnace, then the temperature is raised to 700 ° C., and the temperature is maintained at 700 ° C. for 30 minutes for sufficient degassing of vaporized components. Next, after obtaining a degree of vacuum of about 1 × 10 ⁻² torr, the temperature was raised again to 950 ° C. and 1020 ° C., and held at that temperature for 30 minutes, at which point nitrogen gas was reduced to 3 kg / cm 3. ² flow to quickly cool the sample. Further, after 30 minutes, a degree of vacuum of about 1 × 10 ⁻² torr was obtained, and then the temperature was raised to 250 ° C., kept at 250 ° C. for 2 hours, and then cooled in the furnace.

  The above-described vacuum quenching conditions are the same as those used for quenching a general mold material, and it has been confirmed that even a normal vacuum heat treatment condition can obtain a hardness of up to HMV 600 and can be sufficiently used for a glass fiber reinforced resin.

  The mold material according to the above-described embodiment of the present invention retains the excellent characteristics of the conventional mold material, and at the same time can overcome various problems due to oxidative corrosion when ferritic stainless steel is used as a main material. Since the nitriding treatment is performed, it is possible to control the hardness by a quenching treatment performed thereafter, and it has excellent characteristics as a mold material.

  That is, this mold material has fine pores for ventilation over the entire surface and is excellent in machinability and corrosion resistance. Furthermore, this mold material can be subjected to electrical discharge machining and etching as well as machining. In addition, the mold material can be controlled in hardness by heat treatment.

  As described above, the mold material according to the embodiment of the present invention was able to realize excellent air permeability and workability while maintaining strength. The mold material according to the embodiment of the present invention can also be used for injection molding, which can simplify the mold structure, thereby improving the degassing property and resin fluidity, and molding a defect-free product. it can. That is, a product that has been difficult to be injection molded can be molded. Moreover, the injection molding pressure can be reduced, the molding cycle can be shortened, and gas defects can be prevented. The mold material according to the embodiment of the present invention can also be used for stamping molding and press molding.

Next, a mold breathable member according to an embodiment of the present invention and a method for manufacturing the mold breathable member will be described.
The above-described mold mold material can be used as a mold breathable member by performing electrical discharge machining, etching process, or machining, and this mold breathable member is incorporated into a mold. . Further, the above-described mold material can be used as a mold breathable member by applying a pattern by electric discharge machining, etching process, or machining, and this mold breathable member is incorporated. The molded mold is used for resin injection molding.

  Next, an example in which a mold breathable member is manufactured by electrical discharge machining of a mold material will be described. A resin injection mold for an automobile interior cup holder base was manufactured using a breathable mold member (mold mold material) having the specifications shown in Table 2 as a nested mold cavity.

  In processing the breathable mold member, first, shape processing is performed by machining, and then a copper electrode is prepared, and processing conditions with a surface roughness of approximately Rmax 20 μm are manufactured by Sodick Corporation (EPOC-3). After processing, the processing oil remaining in the pores of the breathable mold member was removed to produce an injection mold.

  An ABS resin was molded with a mold, and the gloss value on the surface of the molded product was measured (gloss meter manufactured by Shiro Sangyo Co., Ltd.). A gloss value of about 4.0 was obtained. The gloss value of a molded product with a mold made of ordinary mold steel is about 10, and the gloss rate is high. In general, a low gloss value in a resin molded product indicates a matte state, and the appearance and feel are improved. For automobile interiors, resin molded products having a moderately low gloss rate are preferred, and by using this breathable mold member, a resin molded product having a very good texture can be obtained.

  Next, an example of manufacturing a mold breathable member by etching a mold material will be described. As in the case of electric discharge machining, a cup holder base resin injection mold was manufactured using a breathable mold member (mold material of Example 1) having the specifications shown in Table 2 as a nested mold cavity.

  In processing the mold breathable member, first, shape processing is performed by machining, and then, prior to performing the etching process, make sure that the etchant does not penetrate into the pores of the mold breathable member. A sealing resin (saved by Koike Oxygen Industry Co., Ltd .; trade name: Dihitoru) was subjected to sealing treatment, and then a typical leather texture pattern for automobile interiors was etched (at Tanasawa Hakkou Co., Ltd.) The injection molding mold was manufactured by removing the dichthal remaining in the pores of the mold breathable member.

  When this mold was used to mold a polypropylene resin and the gloss value on the surface of the molded product was measured (Shiro Sangyo Co., Ltd. gloss meter), a gloss value of about 2.0 was obtained. The gloss value of a molded product with a normal mold steel mold is as high as about 5.5. In general, a low gloss value in a resin molded product indicates a matte state, and the appearance and feel are improved. For automobile interiors, resin molded products having a reasonably low gloss rate are preferred, and by using the mold breathable member according to the embodiment of the present invention, a resin molded product having a very good texture could be obtained.

  Next, a first application example and a second application example in the case where a mold breathable member obtained from a mold material is used for resin molding will be described.

  First, an example in which a short shot is eliminated will be described as a first application example. In the molding of speaker grills made of polypropylene resin for automobile interiors, a grid shape with an opening of 1.5 mm and a wire diameter of about 0.3 mm can be formed normally. Until now, it has been an insert molding of a metal wire mesh. Parts could be manufactured by integral molding of resin.

  Next, an example in which the weld line is eliminated as a second application example will be described. When molding the ABS resin toilet seat, gas in the cavity did not escape from the mold during molding, and a cross or T-shaped weld line was generated. By using a sex member, the generation of weld lines could be eliminated.

  As described above, the mold breathable member according to the embodiment of the present invention achieves excellent breathability while maintaining strength, and can also be used for injection molding. By using this mold breathable member in the mold, it is possible to improve the gas venting and resin fluidity, simplify the mold structure, mold the product difficult to injection molding, molding cycle Can be shortened and gas defects can be prevented. That is, a net-like or lattice-like molded product can be reliably molded, and a thin object can be molded well. Furthermore, since the adhesiveness of the resin to the mold is high, it is possible to form the surface pattern faithfully and to eliminate the gloss unevenness, thus enabling no painting.

  Next, with reference to FIG. 3 thru | or FIG. 6, the manufacturing method of the air permeable member for metal mold | dies by the other embodiment of this invention and its air permeable member is demonstrated. 3 is a partial plan view showing a mold ventilation member according to another embodiment of the present invention, FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3, and FIG. 5 is another embodiment of the present invention. FIG. 6 is a partial plan sectional view showing still another example of the mold ventilation member according to another embodiment of the present invention.

  As shown in FIGS. 3 and 4, a mold breathable member 10 according to another embodiment of the present invention has a cavity 12 corresponding to the product shape formed on one side thereof, and further has a cavity 12 for passing water therein. A plurality of conduction holes 14 are formed. These conduction holes 14 are formed in a straight line, and both ends of the conduction holes 14 are connected by connecting pipes 16, so that cooling water supplied from the outside flows into the conduction holes 14 and the connecting pipes 16. It has become.

  In addition to the linear shape shown in FIGS. 3 and 4, the conduction hole 14 is formed so as to extend in a circuit shape in the mold breathable member 10 as shown in FIG. May be. Further, the conduction hole 14 may be a tank shape as shown in FIG.

  The conduction hole 14 is formed by drilling. The diameter of the conduction hole 14 is preferably in the range of 5 mm to 20 mm.

  Thus, since the water conduction hole 14 is formed inside the mold breathable member 10, there are the following advantages. That is, in injection molding typified by resin molding, usually, heat-melted resin is injected into a cooled mold, cooled and solidified by the mold, and injection molding is performed. . In this injection molding, a small molded product of several grams has a molding cycle of several seconds or less, and even a large molded product such as a bumper of an automobile is molded in several tens of seconds. Since the conduction hole 14 is formed in the mold ventilation member 10 according to the embodiment of the present invention, and the cooling water is allowed to flow through the conduction hole 14, the mold temperature can be kept constant. Thus, stable quality and a molding cycle can be obtained.

  Next, a sealing process for preventing water leakage of the water conduction hole 14 formed inside the mold breathable member 10 will be described. In the case where the conduction hole 14 is formed in the mold breathable member 10 by drilling, if water is passed through as it is, water permeates into the vent hole of the mold breathable member 10 to cause water leakage, and injection molding is performed. It may not be stable and the quality of the molded product may deteriorate.

  In order to prevent such water leakage, the inner surface of the conduction hole 14 of the mold breathable member 10 according to the embodiment of the present invention is sealed with a curing agent-blended epoxy resin. This curing agent-blended epoxy resin is an epoxy resin that begins to cure at room temperature with a curing agent. In this sealing treatment, first, the curing agent-blended epoxy resin is poured from the injection hole of the conduction hole and left for a few minutes, after which the epoxy resin is discharged, and further, the resin remaining inside the conduction hole is cured. After leaving for a certain time, the closing process is completed. Specifically, after forming the conduction hole 14, a curing agent-blended epoxy resin having a viscosity of 200 mPa · s to 20000 mPa · s is preferably poured into the conduction hole 14 and discharged.

  More specifically, the sealing treatment is carried out by using an epoxy resin with an initial viscosity of 500 mPa · s, a mold temperature of 15 ° C. to 25 ° C., a static time of 1 to 5 minutes, and a viscosity of 1800 when the epoxy resin is discharged. It was carried out under the conditions of standing at ˜2500 mPa, 15 ° C. to 25 ° C. for 16 hours or more. In the case of this sealing treatment, it was confirmed that there was no water leak in a pressure leak test at 0.6 mPa.

  Next, with reference to FIG.7 and FIG.8, the air blow washing | cleaning of the metal mold | die air permeable member by embodiment of this invention is demonstrated. FIG. 7 is a front view of a mold breathable member for explaining air blow cleaning of the mold breathable member according to the embodiment of the present invention, and FIG. 8 is a relationship between air permeability and air blow time in the air blow cleaning. FIG.

  In injection molding, a molded product is formed by replacing the air in the cavity with resin. In this injection molding, the mold breathable member according to the embodiment of the present invention is used on the cavity surface of the mold, and the air in the cavity is vented by the vent hole of the mold breathable member. As described above, in order to obtain a mold breathable member, electric discharge machining, etching machining, or machining is performed. By these machining, processing oil or etching liquid is immersed in the air holes that become the ventilation holes. Due to the penetration, this processing oil, etc. loses air permeability and cannot exhibit the effect of degassing, resulting in a problem that causes deterioration in the quality of the molded product.

  Therefore, in the mold breathable member according to the embodiment of the present invention, the processing oil and the etching liquid that have soaked into the vent hole are washed by air blow by electric discharge machining, etching machining, or machining. .

  As shown in FIG. 7, the mold breathable member 20 is disposed in the mold base 24 through the insert 22. An air supply / exhaust hole 26 is formed in the mold base 24, and an air connection groove 28 is formed on the mold air permeability member 20 side of the air supply / exhaust hole 26. A hose joint 30 is connected to the other end of the air supply / exhaust hole 26.

When performing the air blowing process, as a pre-preparation, in order to reliably remove the processing oil soaked in the vent hole after processing and the gas generated during the injection molding, the shape processed surface 10a and the back surface 10b of the mold breathable member 20 In addition, processing that ensures air permeability is performed. In other words, this is a process in which the air permeability becomes 50 cm ³ / cm ² · sec or more. For this machining, electric discharge machining or ball end mill machining is used.

  After completion of this preliminary preparation, as shown in FIG. 7, the mold breathable member 20 is installed on the mold base 24, and in this state, compressed air is supplied from the hose joint 30 to the air supply / exhaust hole 26. The supplied compressed air is preferably 0.2 to 0.8 MPa, and is evenly distributed by the air connection groove 28 to perform the air blowing process.

More specifically, this air blow cleaning is performed by performing electric discharge machining on the upper and lower surfaces (the shape processed surface and the back surface) of the mold air-permeable member having an average air hole of 20 μm, and the thickness in which the processing oil is immersed is different. It carried out using the kind of sample (12 mm, 20 mm). Compressed air of 0.5 MPa was supplied, and the relationship between air blow cleaning time and air permeability was measured. Here, the air permeability is a value obtained by measuring a flow rate per 1 cm ² of compressed air of 0.5 MPa flowing through the sample for 1 second with an integrating flow meter.

As shown in FIG. 8, it was confirmed that the mold breathable member 20 according to the embodiment of the present invention had no change in air permeability after 6 hours of air blow cleaning, and that the processing oil was almost eliminated. Thereby, it was confirmed that oil draining by air blow cleaning was effective. In addition, 2 hours after the start of air blow cleaning, a sample with a thickness of 20 mm has an air permeability of 770 cm ³ / cm ² · sec, and an air permeability of 95% or more after 6 hours is secured. It was confirmed that it was effective to do the above.

  As described above, according to the mold breathable member according to the embodiment of the present invention, the processing oil and the etching liquid immersed in the vent hole are washed by air blow by electric discharge machining, etching machining, or machining. Therefore, it is not necessary to perform complicated work or prepare a special device as in the prior art, and it is possible to clean the processing oil and the like safely and reliably.

  Next, in the air permeable member for molds according to the embodiment of the present invention, ball end milling is performed in order to obtain a necessary surface roughness. The processing conditions with the ball end mill are a rotation speed of 3000 to 30000 rpm, a feed rate of 1000 to 2000 mm / min, a diameter of 0.5 to 10 mm, a feed pitch of 0.1 mm, and a finishing cut amount. Is 0.1 mm.

Moreover, the surface roughness of the process part processed by the ball end mill process of the breathable member for metal mold | dies is 3 micrometers-20 micrometers, Preferably, they are 3.2 micrometers-13.5 micrometers.
Furthermore, the air permeability of the mold breathable member obtained by ball end milling is 100 to 2000 cm ³ / cm ² · sec.

  When electric discharge machining is performed so as not to clog the mold breathable member, the surface roughness becomes rough, and the resin injection molding has a problem that the mold release resistance at the time of die cutting is large. However, since the mold breathable member according to the embodiment of the present invention is processed by the ball end mill under the above-described conditions, the surface roughness is 20 μm or less, and the mold release resistance at the time of resin injection molding can be reduced. It has become easy to ensure dimensional accuracy in precision injection molded products. Therefore, it can be applied to fields that have been difficult to use, such as rib shapes.

10, 20 Breathable member 12 for mold 12 Cavity 14 Conducting hole 16 Connecting pipe 22 Nest 24 Mold base 26 Air supply / exhaust hole 28 Air connecting groove 30 Hose joint

Claims (11)

A green body is produced by forming a mixed material including a stainless steel fiber having a diameter converted diameter of 30 to 300 μm and a length of 0.4 to 5.0 mm and a stainless steel powder,
The green body of this mixed material is heated and sintered to make a sintered body,
This sintered body is heated under a nitrogen atmosphere to produce a mold material having holes having an average hole diameter of 3 to 50 μm,
This mold material is machined to produce a mold breathable member having a surface roughness of 3 μm to 20 μm,
The air-permeable member is washed by air blowing so that the air-permeable member has an air permeability of 50 cm ³ / cm ² · sec or more,
Drilling the breathable member to form a conduction hole having a diameter of 5 mm-20 mm in the breathable member;
A method for producing a mold-permeable air-permeable member, in which a void formed in a conduction hole is sealed by pouring and discharging a curing agent-blended epoxy resin having a viscosity of 200-20000 mPa · s into the inner surface of the conduction hole. Machining of the mold for the air-permeable member is performed by a ball end mill, the rotational speed of the ball end mill is 3000～30000Rpm, feed speed of the ball end mill is 1000 to 2000 mm / min, according to claim 1 Manufacturing method of air-permeable member for mold. The manufacturing of the air permeable member for molds according to claim 2 , wherein the processing of the air permeable member for molds by a ball end mill is processing in which the air permeability of the air permeable member is 100 to 2000 cm ³ / cm ² · sec. Method.   Drilling to form a conduction hole in the mold breathable member includes a step of drilling the mold breathable member to form a plurality of conduction holes each having an inlet opening and an outlet opening on opposite sides. Furthermore, the manufacturing method of the ventilation member for metal mold | dies of Claim 1 including the process of connecting the exit of a conduction hole, and the entrance of the adjacent conduction hole.   The method for manufacturing a mold breathable member according to claim 1, wherein the stainless steel fiber and the stainless steel powder of the mixed material are ferritic stainless steel. 2. The mold vent according to claim 1, wherein a nitrogen content of the sintered body in a nitrogen atmosphere is 0.3 to 1.2 wt% with respect to 100 wt% of the stainless steel component after heating in the nitrogen atmosphere. A method for manufacturing a structural member.   The method for producing a mold breathable member according to claim 1, wherein the mixed material further contains copper powder or copper tin alloy powder. The mixed material includes, as a stainless steel component, 20 to 80% by weight of stainless steel fiber and 20 to 80% by weight of stainless steel powder, and further, 1 to 10% by weight with respect to 100% by weight of the stainless steel component. The manufacturing method of the air permeable member for molds of Claim 7 containing a copper powder or a copper tin alloy powder.   The method for producing a mold breathable member according to claim 1, wherein the porosity of the holes is 15 to 35%.   The method for producing a mold breathable member according to claim 1, wherein the heating of the sintered body in a nitrogen atmosphere is performed while being held at 900 to 1050 ° C in nitrogen gas or ammonia decomposition gas.   The method for producing a mold breathable member according to claim 1, wherein the surface roughness is 3.2 μm to 13.5 μm.

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